Monolayer　HNb3O8　2D　nanosheets　have　been　used　as　highly　chemoselective　and　active　photocatalysts　for　the　selective　oxidation　of　alcohols.　The　nanosheets　exhibit　improved　photocatalytic　activity　over　their　layered　counterparts.　Results　of　in　situ　FTIR,　DRS,　ESR,　and　DFT　calculations　show　the　formation　of　surface　complexes　between　the　Lewis　acid　sites　on　HNb　3O8　2D　nanosheets　and　alcohols.　These　complexes　play　a　key　role　in　the　photocatalytic　activity　of　the　material.　Furthermore,　the　unique　structural　features　of　the　nanosheets　contributed　to　their　high　photocatalytic　activity.　An　electron　transition　from　the　coordinated　alcohol　species　to　surface　Nb　atoms　takes　place　and　initiates　the　aerobic　oxidation　of　alcohols　with　high　product　selectivity　under　visible　light　irradiation.　This　reaction　process　is　distinct　from　that　of　classic　semiconductor　photocatalysis.　©　2014　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim.